冲击电压下500 kV油浸倒置式电流互感器局部放电特性研究

Research on Partial Discharge Characteristics of 500 kV Oil-immersed Current Transformer Under Impulse Voltage

为了研究油浸式电流互感器在运行过程中的局部放电特性,搭建500 kV油浸倒置式电流互感器在冲击电压下的局部放电试验回路,对试品施加标准雷电冲击电压和操作冲击电压,使用安装在试品末屏接地引下线处的非接触式高频局部放电传感器采集局部放电信号,通过高采样率示波器显示放电波形。在冲击试验后进行工频局部放电测量、油中溶解气体成分分析、高电压介质损耗因数测试、频域介电谱测试,以检测试品的绝缘状况。研究结果表明:油浸式电流互感器在冲击电压下发生局部放电,绝缘损坏,放电熄灭电压低于正常运行电压,放电无法自熄灭,长期累积作用造成设备故障。

To study partial discharge(PD) characteristics of the oil-immersed current transformers during the operating process, the PD test circuit of 500 kV oil-immersed inverted current transformer in impulse voltage was established, and standard lightning impulse voltage and switching impulse voltage were applied to the test object. The partial discharge signal was acquired by the non-contact high frequency partial discharge sensor installed at the grounding lead down of the terminal screen of the subject. The discharge sensor took a partial discharge signal and showed the discharge waveform through a high sampling rate oscilloscope. After the test, power frequency partial discharge measurement, dissolved gas composition analysis in oil, high-voltage dielectric dissipation factor test and frequency-domain dielectric spectrum test were used to reflect the insulation status of the tested product. The results show that the partial discharge is found in the impulse voltage, and the insulation is damaged. The discharge extinguishing voltage is lower than the normal operating voltage, the discharge cannot self-extinguish, and the long-term cumulative effect causes equipment failure.